I think this is over engineering. It is cool, but I am not sure if it is practically needed.
1. If you come back home everyday then you can yourself check the watering requirements.
2. If you go out for a couple of weeks, you could ask/get from somewhere the watering requirements of the plant and then give it water at fixed intervals. I think that will work too.
3. The amount of time you spent on doing this, in that time you could honestly learn about watering requirements of plants. And that is something different to know compared to knowing how to write cool code.
Perhaps the point of all this was not watering the plant, but the engineering itself? Looks like a very fun and inspiring thing to do, I'd love to do some of that one day just to learn the electronics.
